Dovecot is an open source and free POP3 and IMAP server that can be successfully deployed on Linux and UNIX-like operating systems. Written with security primarily in mind, the Dovecot project is easy to set up and doesn't require special maintenance.
The highest performing IMAP server
Dovecot is also one of the highest performing IMAP servers, standards compliant, providing self-optimizing indexes and self-healing. It’s admin-friendly, features flexible user authentication, migration support from many existing POP3 and IMAP servers, as well as workarounds support for POP3 and IMAP bugs.
It is standards compliant
While other email servers fail most of them, the software compiles with all IMAP (Internet Message Access Protocol) server standard tests. It has been engineered to offer self-optimized indexes that contain all the data and information that the client used by the end-user usually needs.
The best feature of Dovecot is its ability to self-heal whenever an issue arise. For example, it will try to fix broken index files. However, serious problems are automatically logged in a log file that is accessible to the sysadmin. Additionally, the program aims to be admin-friendly.
Mailboxes and indexes can be modified
Another interesting features is the ability to allow users to modify indexes and mailboxes from multiple computers at the same time, which means that it works perfectly on clustered filesystems. In addition, director proxies are used to fix common NFS (Network File System) caching problems.
Extremely flexible user authentication
Above all the aforementioned features, Dovecot also comes with an extremely flexible user authentication that has been designed from the offset to support a wide range of authentication mechanisms and databases.
It’s easily extensible
Another great feature of Dovecot is its ability to extend itself with new features via plugins. IMAP and POP3 accounts from other email servers can be easily imported in Dovecot. It is a very secure email server for the 21st century.